In recent years, in the art of photomechanical process, it has been desired to use a photographic light-sensitive material excellent in original reproducibility and a processing system which can operate with a reduced amount of waste liquid to be disposed so as to cope with diversification and complexity of printed matters and the increase in environmental awareness.
In order to obtain good reproduction of a halftone image in continuous gradation or of a line work, an image formation system exhibiting an ultrahigh contrast (particularly having a .gamma. value of 10 or more) photographic property is required.
For forming a high contrast image, a lithographic development system employing a so-called "infectious development effect" has been commonly used. However, the lithographic development system is disadvantageous in that the developer is too unstable to be used. An image forming system has been desired in which the photographic light-sensitive material is developed with a processing solution having a good storage stability to obtain an ultrahigh contrast. Examples of such an image forming system are described in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,269,922, 4,272,606, 4,311,781, 4,332,878, 4,618,574, 4,634,661, 4,681,836 and 5,650,746. In this image forming system, a surface latent image type silver halide photographic light-sensitive material comprising a hydrazine derivative incorporated therein is developed with a stable MQ or PQ developer having a Ph value of from 11.0 to 12.3 to obtain an ultrahigh negative image having a .gamma. value of more than 10. In accordance with the method, an ultrahigh contrast and a high photographic sensitivity can be obtained. Further, since a sulfite can be added to the developer in a high concentration, the developer thus obtained exhibits a remarkably improved stability against air oxidation as compared with the conventional lith developers.
The above described method makes it possible to use a sulfite preservative in a high concentration to increase the stability of the developer. However, in order to obtain an ultrahigh contrast photographic image, it is necessary to employ a developer having a relatively high pH value. Such a developer having a relatively high pH value is liable to air oxidation. Thus, it is necessary that the developer be replenished at a high rate. Therefore, some attempts have been made in order to realize an ultrahigh contrast photographic image forming system comprising the nucleation development with a hydrazine compound by using a developer having a lower pH value.
U.S. Pat. No. 4,269,929 (corresponding to JP-A-61-267759 (the term "JP-A" as used herein means an "unexamined published Japanese patent application")), U.S. Pat. No. 4,737,452 (corresponding to JP-A-60-179734), U.S. Pat. Nos. 5,104,769, 4,798,780, 4,998,604 and 4,994,365, JP-A-1-179939, JP-A-1-179940 and JP-A-8-272023 describe a process which comprises the use of a hydrazine nucleating agent having high activity and a nucleation accelerator in order to obtain an ultrahigh image with a stable developer having a pH value of less than 11.0. It is also described that a chemically-sensitized silver halide emulsion having a high silver chloride content has high nucleation activity.
However, another problem encountered when the above described highly active hydrazine nucleating agent, highly active nucleation accelerator or highly active emulsion is employed is the occurrence of a so-called processing unevenness which is density unevenness caused in outputting at defined dot area.
Also, the photographic light-sensitive material containing the highly active hydrazine nucleating agent described above is troublesome in the preservation thereof for a long period of time since the highly active hydrazine nucleating agent is disadvantageously liable to decompose.
Further, although the amount of replenishment for developer and the amount of waste liquid in processing decrease to a certain extent using the stable developer having a pH value of less than 11.0, still further reduction is required. Therefore, a photographic light-sensitive material having higher processing stability, which has less change in photographic properties due to fluctuation of pH of a developer has been desired.
The incorporation of a hydrazine nucleating agent into fine polymer particles to add to a coating solution is described in JP-A-2-948. However, a purpose of the technique is prevention of deposition of the hydrazine nucleating agent.